of rochester



N. T. POWELL Dec. 1, 1925.

AUT OMATIC TELEPHONE SYSTEM FlGE HOLD

INVENTOR WIHFRED T. PQWELL.

SW TCH TALKING CCT.

ATTORNEY lt' atentecl UNITED STATES PATET E'Fltfllil.

'W'INFRED T. POWELL, OF ROCHESTER, NEW? YORK, ASSIGNOR TO THE STROMBERG-CARLSO N TELEPHONE MANUFACT UR-I A CORPORATION OF NEW YORK.

NG COMPANY, OF ROCHESTER, NEVT YORK,

AUTOMATIC TELEPHONE SYSTEMI.

Application filed January 18, 1922.

'1 0 all iii/1.0m. it may concern:

Be it known that I, l i lrrrnnn 'l. POWELL. a citizen of the UnitedStates. residing at tochestcr, in the county of Monroe and State of NewYork, have invented certain new and useful Improvements in AutomaticTelephone Systems, of which the following is a full, clear concise, andexact description.

This invention relates to telephone systems and more particularly totelephone sy tems in. which automatic switches are employed in.completing some portion of telephone connections.

The purpose of the present invention is to provide a telephone system ofrelatively small capacity, the circuits of which are relativelyinexpensive to install and are siin pie to maintain in operation.

The various features of the invention will appear from the detaileddescription and a ppcn (lflll claims.

In the drawings Fig. l diaera]mnatically represents the circuits andequipment necessary :tor three telephone lines. The equipment for eachline is separated from that ot the other tclci hone lines by dottedlines and i it entities of the drawing. l ig'. 2 shows a detail ot themechanical structure of the i omatic switch which is provided for eachtelephone line. Fig. 3 is a schematic showing ot' the talking circuitcompleted between two tclophmic lines.

lathis stcm each telephone line is proid'=- with an individual numericalswitch thr ugh the terminals ot which. any other telephone line ot thesystem may he reached. The st ructure of this switch may hesubstantially similar to that disclosed in the patent to llullardzly'rlaltll'htlili patented .i'l-iugrust ii. cczept that the armaturesand pawls the retaining magnet l and the stepping magnet o are notllltGl'lOCkll'lQ, but are oil. the arrangement substantially similar tothat disclosed in Flog. 2 ot the present disclosure. lly rci'crencc tothe patent to Bollard. it will be noted thatthc stepping nia ri'iot suchas (3 advances the pair of switch wipers herein (it "7 and ti over theirrespective sets terminals. The stepping magnet 6 normally retains itsstepping pawl out of engagement with. the ratchet wheel 2 of the SerialNo. 530,115.

switch and the retaining or holding magnet l likewise normally holds itspawl out of engagement with the ratchet wheel. 2 and as will appear inthe course of this description the operating pawls engage the ratchetwheel only during the time that its switch is in use.

The substation circuits of this system are of the type now well known inthe art and are usually referred to as the local second.- ary type,since the receiver is in a circuit local to the substation and seriallyincludes a secondary winding of an induction coihthe primary winding ofwhich is in series with the central source of energy and also with thetransmitter.

In this system an impulse sender is employed which may be of any wellknown structure and in which a set of in'ipulse springs isintermittently operated to cause a series of line interruptions commonlyknown in this art as impulses. The structure oi. this impulse sender. itthe system is of relatively small size, (that is not over ten lines) orit the individual switch is three tively ope 'ated in response toseveral series of impulses, may he of the structure substantiallysimilar to the impulse sender or dial such as is shown in the patent toKeith l:1,279. 352. issued September 17, 1918. If. however, the systemis arranged for more than ten subscribers lines and it is still desiredto directively set the subscribei."s individual switch in response toone adjust ment of the impulse sender then it will he desirable toemploy an impulse sender ol? the type disclosed in the patent to Lattip;#LOElOAlQ, issued June 1912. The impulse sender previously ret'erred tois dia grammatically represent-ed lov a series of contact springs shownwithin the circle associated with each substation. circuit. The purposeo1 these various sets of springs will appear in the course of thepresent description.

The ringer or signal pr yided at each suhstatimi is commonly known inthe art as a direct ctu'rentrinoger such as is normall employed incertain interconnnunicati ,5 telephone ."stems,or may he similar to theordinary door hell ringer,

Yfith this-descriptlon the @Pl and certain of the circuitsassociatedtherewith, it is believed that the operation of the systemwill best be understood by describing the method of establishing atelephone connection from the subscrlbers substation designated A to asubscribers line the substation circuits of which are herein designatedB. lVhen the subscriber at A removes his receiver from its switch hook,the contacts 10 are closed, thereby completing a circuit from ground,winding of the ringer magnet 11., through the t-ransi'mtter and primarywinding of the induction coil, impulse springs 12 of the impulse sender,contacts 10, winding of the stepping magnet to grounded battery. Underthe con trol of this circuit the stepping magnet advances its brushes 7and 8 from their home position, to the next set of terminals hereinreferred to as a normal position of the switch. As soon as the steppingmagnet 6 is energized itcloses an operating circuit for the slowreleasing holding magnet 4 extending from grounded battery winding ofthis magnet, front contact and armature of magnet 6 to ground. Thesubscribers individual switch is now in condition to receive a directiveseries of impulses from the impulse sender. Since it has been as sumedthat the connection is to be made to the line of the subscriber at B, itis necessary to transmit a series of two impulses from the impulsesender at substation A. This impulse sender is thereby adjusted to sendtwo impulses and this adjustment, as is well lrnowi, results in theclosure of the sets of contacts 13, 14 and 15 and subsequently in theintermittent closure of the set of impulse springs 12. The closure orthe contacts 1% and 15 serves to short circuit the ringer magnet 11 andto connect ground to the impulse springs 12. This completes a substitutecircuit for the step ping magnet 6 extending from grounded batterywinding of this magnet, contact springs impulse springs 12 and springs14- and to ground. When in the course of the operation 01 the imp'ulsesender it opens its springs 12, the stepping magnet 6 will retract itsarmature, but the holding magnet 4t will maintain the switch in theposition to which it has been advanced. .skhnost immediately after theopening of the impulse springs 12, they will again be closed to completethe operating circuit of the stepping magnet 6 with the result that thebrushes 7 and 8 are advanced from the so-callet normal position intoposition 1. In response to the next impulse from the impulse sender. thestepping magnet 6 will be deenergized as described but a circuit willsoon after he completed by the closure of the impulse springs 12 so thatthe stepping magnet 6 will advance the brushes 7 and '8 into engagementwith; the

#2 set of line terminals. The impulse sender has now completed thetransmission of the series ofimpulses and its sets of contact springs12, 13, 1%. and 15 will be in their normal condition, that is thecondition in which they appear in Fig. 1.

It will be noted that as soon as the step ping magnet G deenergizesafter the holding magnet l has been operated, an actuating circuit isclosed for the cut-off relay 16, extending from grounded battery, lowerwinding of this relay, front contact and armature of magnet 4, backcontact and armature of stepping magnet 6 to ground. The cut-oil relay16 is energized in this circuit and is locked operated as long as theimpulse sender springs 13 and 1% are closed. This locking circuit may betraced from ground, springs 13 and 1 1, conductor 17, lower armature andfront contact of relay 16, armature and contact of magnet 4, lowerwinding of cut-oi? relay '16 to grounded battery. At the close of theseries of impulses, the sender springs 13 and 1e are opened to permitthe release of relay 16. 5

The previously described operation of the automatic switch individual tothe calling line has advanced the brushes 7 and 8' into engagement withthe terminals 18 and 15) of the wanted subscribefis line. It ,will firstbe assumed that this line is idle so that when the subscriber at Asignals the subscriber at B by depressing the ringing button 20, aringing circuit is closed from grounded battery, winding of the steppingmagnet 6, switch hook springs 10, ringing button 20, conductor 17, lowerarmature and bacl: contact of cut-oil relay 16 switch brush 8, which isnow in engagement with the multiple terminal 1-), conductor 21, brush 22of the wanted subscribers switch, lowermost contact and armature of theoutofi" relay ..3, conductors and back contact, armature and winding ofthe ringer magnet 26 to ground. It will thus be seen that aself-interrupting circuit is closed for the ringer magnet 26, whichcauses it to vibrate its armature and actuate the bell at the wantedsubscribers station. At this time condenser 3% serves to quench thespark at the contacts of ringer magnet 26. The alternating currentgenerated by the operation of the ringer magnet 26 causes a tone to beheard in the receiver at the substation at A so that the subscriberthereat can tell that the wanted subscriber is be ing signaled. When thewanted subscriber at B answers by removing his receiver from its switchhook the ringing of lllS bell is immediately stopped since the ringermagimpulse springs 2?, switch hook springs 28,

winding of the stepping magnet 29 to grounded battery. The steppingmagnet 29 is also energized in this circuit and ad- 'Vt nc the brushes30 and 22 ot the wanted subscl'ribcr s switch to the so called normalposition that is in engagement with the terminals 31 and 32. Thesubscribers s Witch is therefore advanced from its home position so thathis telephone line cannot be seized by some other subscribei."s switch.

The telephone connection is now complete between the substations at Aand B and the talking battery tor the ailing; subscriber supplied over acircuit from grounded battery through the winding; of the steppingmagnet 6, switch hooh springs 10, inn iulse springs 12, primary windingof the iudu tion coil" through the transn'iitter, winding of the ringermagnet 11 to ground. 'lalhing' battery for the called subscriber issupplied from grounded battery winding of the stepping;- magnet 29,switch hook springs 28. impulse springs 27, primary winding of the int.ction coil; through the called subscribers transnntter and w nding' otthe ringer magnet 26 to ground. lit will be noted that ringer magnets 11and 26 are ope'ated at this time to remove the short circuit fromcondenser; 33 and 3 1. It will thus be seen that the ringer magnets 11and 26 also t inction as impedance coils for the talking; circuit. Itwill further be understood that the condensers such as 323 and 31!;serve to inductively connect and conductively separate the conre'sational circuit exteiuling between the cal iu and wanted iuiliscriheil it now be a i tt-riniuatingr at s1 tation i3 uh idy engagedinconi'erszt u and that this line busy as a called line. its set ()1hrushei-i 9 I 1 nd 30 will. there tore be in en asement with describedthe terminals 31 and a as nice: or

s: that the ringing: circuit preiiouslv dei-zcrihed as includingcoinluctors 724i: and will not be conugleted and conseipuintty no ri tring tone will be heard in the calling sub l scriheifs receiver. The:taiiure to hear {iii-5 tone after the extension ot the co:inection is asi nal to the calling; party that the wantcc li..e is busy. This is inthe nature ot a negative signal but one which is etiective when the SlJJSQlllJtEi'S are ins ructed as to the opcrmtion oi. the 'steni.

lit nil be ,a. dd that the cut-oil lt calling line locl zed en.

stinent ot the caliin cit-ch in 1 it the called line is bus}; due in fl--t w act Liar In nasiictli prev ens sci/lo her line. such as thatterminating at ion te this i. tag-r will be loclted operthe call i hsubscriber disconnects. e circuit for this relay now extends from groundarmature and troutcontact of may iiet upper winding: uo er trout contactand miniature of relay it), switch brush i,

terminal 18, multiple terminal 35, brush 56 ot the subscribefls lineterminating at G, upper armature and back contact or cut-oil relay 37,winding of the stepping magnet 38 associated with the C subscribersindividual switch, to grounded battery. Under the con trol of thiscircuit the cut-ed relay 16 is locked operated and prevents thecompletion of the ringing circuit over conductor 1.? and this insuresthat the connection now established between substations and Q will notbe disturbed.

It the line terminating at B substation is busy due to the fact thatthis line has originated. a call, the brushes 22 and 30 of itsassociated so itch will be ad anced beyoi their so called home andnormal posi tions so that the ringing circuit tor the substation A willvnot be completed with the result that the it subscriber can hear noringing tone and will know that the wanted line -annot be reached.

At the close of the conversation the *alling subscriber at A restoreshis portion of the established connection by simply replacing hisreceiver on its switch hook thereby opening the switch hook springs withthe suit that the steppiin; magnet 6 deci'iorgnzes and shortly utter tneslow releasing n agnet -xl deenergrizes. This permits the 'eiract respring of its associated switch to restore the brusliies "Z and 8 ctthis switch to their home on. Similarly when the called .ulr atsub-station l3- rcplaccs his revolver on its switch hook, springs areopened to permit the z-steppinp; magnet to decncrggizc and shortlyatterwards the slow releasing holding magnet -10 of this switch decne sothat the retractive spring of the 1...:T subscriber's switch. restoresthe brushes 2:2 and oi this switch to their normal positiou.

ll hile the subscribefis individual switches have not been(itfii'liiitti in deia'l operating); on the cumulative ncipl it is to beunderstood that these switches i ray be so opcrated without any chancein t 1e operating circuits. .iiutoinatic switches operated on cumulativepriuci iilc are also reterrcd to adding type switches and un bedescribed as advanc' uai to the in; um

I a number ()5, steps cu :uun oi. the im iiulses in sereral series ofimf JttlSLS, instead of being} advanced in the well known group andline. selcctin increments.

it will thus be seen that a. simple ttlit0- inatic telephone system isprovided in which a ininnnuin amount of equipment is used and in whichrelatively simple (operative circuits a re employed.

automatic telephone system. a irality of telephone lines. a subst; tionfor telephone line. a. telephone transmitter. .4. e iihone receiver anda ringer magnet at. each i-iubstatimi, a pin 'ality oi automaticswitches, each automatic switch having passive contacts and activecontacts ar 'anged to be progressively advanced over said passivecontacts. a motor magnet for advancing the active contacts oi eachswitch, each telephone line terminating in the active contacts oi oneautomatic switch, certain of the passive contacts ot said automaticswitches being multipled together, means associated with the callingsubstation for directively controlling the operation of its assiciatedautomatic switch for extending said calling tclephcme line to a vantedtelephone line, a common source of current, and means including circuitshaving therein the impedance oi the motor n agnets and ringersassociated with the calling and talled telc phone lines tor connectingsaid source of cur rent to the telephone transn'iitters of these lines.

2. In an automatic telephone system, a plurality of telephone lines, asubstation for each telephone line, a telephone transmitter, a telephonereceiver, a ringer magnet and a ringing key at each substation, aplurality of automatic switches, each automatic switch having passivecontacts and active contacts arranged to be progressively advanced oversaid passive contacts, electromagnetic means it advancing the active.contacts of each switch, each telephone line terminating in the activecontacts of one automatic switch certain of the passive contacts 01 thesaid auton'iatic switches being multiply connected tog ctlwr meansassociated vith the calling suhstation tor controlling the operation oithe el etromagnetic means of its automatic switco tor extending saidcalling substation to a wanted substatiom a ringing circuit including:the rin r magnet at the suhstation, means including the ringing L at thecalling substation, tor controlling said circuit. a common source ofcurrent, and n'ieans including a circuit having; therein the impedanceof said electromagnetic means and the ringer magnets associated with thecalling and called telephone lines tor cminectin r said source otcurrent to said transmitters.

in an automatic telephone system, a plurality oi telephone lines, asubstation tor each telephone line each substation havinc a telephonereceiver, a telephone trammitter and a ringer magnet, a plurality 0tautomatic switches each automatic switch having passive contacts andactive contacts arrang' d to be progressively advanced over said pasivecontacts electromagnetic means for advancing; the active CODt-tCtTS ofeach switch, each elephone line terminating: in the active contacts ofone auton atic switch, cer am of said passive contacts being multiplycomected together. means associated with a calling substationdirectively control lins the operation of the electromagnetic means ofits associated switch for extending said callii substation to a wantedsubstation a conin'ion source of current, means including Zrcuits havingtherein the impedance of the electromagnetic means and the ringermagnets associated with the calling and called telephone lines forconnecting said source of current to their transmitters and meansincluding a condenser at each substation ot a completed connection for cinductively separating said transn'iitter circuits from each other.

4. In an automatic telephone system a arality ot telephone lines, ea htelephone 1c being); provided with a transmitter and a receiveri meansincluding an automatic switch individual to a telephone line tor ex-LtlltllllQ said telephone line to any ot the other telephone lines. aconunon source ot current; means iucliulin; portions of the calli andcalled telephone lines for supplying current to the transmittersassociated with said telephone lines, and means including condensmslocated at the calling and called substations tor inductively connectinghut conductivcly separatiim' the telephone "ransers of an establishedconnection 5.111 an automatic telephone system. a plurality of telephonelines a substation associated with each telephone line, each substationbeing provided with a telephone receiver, a telephone transmitter and acall signal, an automatic switch individual to each telephone line forextending said telephone line to any of the other telephone lineselectromagnetic means arranged to he directively controlled from acalling substation for directively operating the automatic switch of acalling telephone line to extend said line to any i 'anted telephoneline, means including a circuit extending over said calling and calledtelephone lines through said automatic switch tor establishing atelephonic connection between the telephone receivers and transn'iittersat the calling and alled substations, and a second circuit including aportion of said first circuit for actuating the call signal at thewanted substation, said circuit serially including the electromagneticmeans of said last mentioned switch.

6.111 an automatic telephone system a plurality of telephone lines asubstation. for each telephone line having a telephone re ceiver atelephone transmitter and a call signal an automatic switch individualto each telephone line for extending said telephone line to any of theother telephone lines, electromagnetic means associated with saidswitch, said electromagnetic means being directively controlled over acalling telephone line, a common source of current, 11 cans includingsaid source of current for actuating the call signal at the wantedsubstation, means operated simultaneously with said ltltl llt) llS

messes walled signal for causing a tone in the ceivcf at the callingsubstation, and nicer-s for connecting uaid source of current to ttelephone tr: iin'iitters oi the cstablisl ed connection.

7. In an automatic telephone system, a plurality of telephone lines, asubstation having a transmitter for each telephone line, an automaticswitch indi idual to each telcphone line for extending said. telephoneline to any ot the other lines, incai'is t'or dircr tivcly ope'atingi;each automatic switch, a common source ot curreit, and circuits forconnecting said source ot current to the transnnitters ot a completedtelephone connection, said circuits each including a current teed coiland a winding of an iiuluction coil at each of the substations of thetelephone connection.

8. In an automatic telephone system, a pluralit of telephone lines, asubstation for each telephone line having a telephone transmitter, atelephone receiver and a call signal, a n automatic switch for eachtelephone line" means for directively operating each automatic s'vitch:lor cnniecting said tcle phone line to any other telephone line acon'n'non source of current or said tcle honc transmitters and callsignals, means uicluding a portion ot the calling and called telephonelines for causing said source o l? cuu rent to actuate the called signaland interrupt its own circuit at the wanted sulr-ztation, a telephonecircuit interconnecting the calland called telephone line, said circuitincluding the transmitters of said telephone lines, a condense f at eachoi"- the substations of the associated connections for conduc tivelydividing said telephone circuit into two parts, one part including each.trznsinitter, means for bridging said source of current to eachtransmitter, and means in cluding the mentioned condenser associatedwith the called siiibstatiim tor quenching the sport; at theiutern'iittmitlr opts-a ling culled. s i gn a] 9.111 an automatictelephone system, a plurality of telephone lines, a telephonetransmitter, a telephone receiver and a call. signal for each telephoneline, an auton'iatic switch individual to each telephone line torconnecting said telephone line with any t (Y the other telephone lines,directively con trolled means for operating each individual switch forcausing it to seize any wanted telephone line, a call signal a eachsubstation, electromagnetic means including a e tinterrupting circuitfor actuati.,..; the ll signal at a wanted substation, manual means atthe calling substation for controlling said circuit, a condenser at eachsubstation nor mally bridged about the contacts of said electromagneticmeans, and means tor continuously energizing the electromagnetin'icansat the calling and called sub tations during the n'iaintenau -e of atelephone (Ullnection.

it). in an autmnatic telephone plurality oi" telephone lines, a eachtelephone line, a telephone trausui a receiver and a ringer inagi'ictineach ittcr, sul station, a plurality ot autinnatic switches forinterconnecting said telephone lines, a

or l'lllt"tt for advancing each automatic s us inchidiug one of saidswitches and its motor magnet for extending one of said telephone lineswhen calling to a fluted telephone line, a coalition source 01 v:'urrent, and n'ieans including a circuit having therein the impedance ofsaid last mentioned niotor magnet and the ringer magnet of the ailingtelephone line for connecting said. source of current to the telephonetrans niit-ter of aid calling telephone line.

it. in an automatic telephone s: tent, a plurz lit-y oi telephone lines,each telephone line being provided with a transmitter and a receiver,means including an automatic switch for extending a calling telephoneline to any oi? the other telephone lines, a common source of current,means including portions of the calling and called telephone lines forsupplying current to the transmittic assi'iciatcd with said telephonelines, and is including condensers located at the called and callingsubstations :t'or inductivel connecting and conductively .eparating t retelephone tr: nsinitters of an established telephone connection.

123. In an automatic telephone system, a plurai'ty of telephone lines, asuhstation tor each telephone line having a telephone receiver, atelephone transmitter and a call signal, an automatic switch forextending a telephone line when calling to any of the other telephonelines, elect-r magnetic means associated with said switch, saidelectromagnetic means being direct-i'vcty controlled by a ailingtelephone line, a source of current, ringing lllQttt'lS including; saidsource ot cur-- renttor actuating said all. signal at the wanted.substation, means ope 'ated simultaneouslx with said called sipnial forcausing a tone in the receiver at the calling substalion, and meansincluding a portion of said ringing means for connecting said source ofcurrent to the telephone transmitters 01" the established connection.

13. ltn an automatic telephone system, a plurality of telephone lines, atelephone transmitter, a telephone receiver, and a call signal for eachtelephone line, means in cluding an automatic switch for connecting atelephone line when calling to any other telephone line, directivclycontrolled means for operating saio automatic switch for causinn it toseize a wanted telephone line, electromagmatic ineai'is including aselt-interruptinn circuit tor actuating the cell signal at a rantedsulrstation, manual. means at the calling substation for controllingsaid circuit, condensers at each substation normally bridged about thecontacts of said electromagnetic means, and means including a portion ofsaid self-inten'upted circuittor continuously energizing theelectromagnetic means at the calling and called substation during themaintenance of the telephone connection.

In witness whereof, I hereunto subscribe 10 my name this 17th day ofJanuany A. D. 1922.

XVINFRED T. POXVELL.

